Making ethanol by fermentation
3 marks · EasyA student carries out fermentation at different temperatures. The table shows the volume of ethanol made after 3 days.
| Temperature (°C) | Ethanol produced (cm³) |
|---|---|
| 15 | 12 |
| 25 | 30 |
| 35 | 33 |
| 45 | 10 |
At which temperature was the highest volume of ethanol produced?
Suggest why the volume of ethanol is lower at 45°C.
How does temperature affect the rate of fermentation based on this data?
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) 35°C
(b) Enzymes are denatured at high temperature / yeast stops working
(c) Rate increases with temperature up to 35°C, then falls at higher temperatures
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States 35°C.
B1 (b) · 1 mark · Mentions enzymes denature or yeast stops working at high temperature.
B1 (c) · 1 mark · States rate increases with temperature to a maximum, then decreases at high temperature.
Worked solution
a) The highest ethanol was produced at 35°C.
b) At 45°C, enzymes in yeast are denatured, so less ethanol is made.
c) The rate of fermentation increases as temperature rises up to about 35°C, then drops at higher temperatures.